The present invention relates to blooming filters, and more particularly, to blooming filters for multiple exposure high dynamic range image sensors.
A multiple exposure method can be used to produce high dynamic range images. High dynamic range images are images with a high brightness contrast. Multiple images may be taken that have different exposure times. Typically, long exposure images can better capture low-lit parts of a scene and short exposure images can better capture bright parts of a scene. The multiple-exposure images are combined during image processing to form a high dynamic range image.
Conventional image processing methods often minimize the contribution of saturated pixel values to the final image by using pixel values from short-exposure images for bright portions of a scene. However, photons that are received at saturated pixels may cause charge to overflow onto neighboring pixels, in an effect that is known as blooming. Pixel values that are distorted by blooming charge effects may have nonlinear values and may create image artifacts. Conventional image processing methods do not take into account blooming effects when processing multiple exposure high dynamic range images.
It may therefore be desirable to have improved methods for processing multiple exposure high dynamic range images that reduce the effects of blooming.